java.lang.NoSuchMethodError: org.objectweb.asm.ClassReader.accept(Lorg/objectweb/asm/ClassVisitor;I)V
at com.springsource.bundlor.support.asm.AsmTypeArtefactAnalyser.analyse(AsmTypeArtefactAnalyser.java:43)
at com.springsource.bundlor.support.StandardManifestGenerator.analyzeEntry(StandardManifestGenerator.java:116)
at com.springsource.bundlor.support.StandardManifestGenerator.analyzeEntries(StandardManifestGenerator.java:101)
at com.springsource.bundlor.support.StandardManifestGenerator.generate(StandardManifestGenerator.java:66)
at com.springsource.bundlor.ant.internal.AntBundlorExecutor.execute(AntBundlorExecutor.java:73)
at com.springsource.bundlor.ant.Bundlor.execute(Bundlor.java:106)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
at org.apache.tools.ant.TaskAdapter.execute(TaskAdapter.java:154)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
at org.apache.tools.ant.Task.perform(Task.java:348)
at org.apache.tools.ant.Target.execute(Target.java:390)
at org.apache.tools.ant.Target.performTasks(Target.java:411)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
at org.apache.tools.ant.helper.SingleCheckExecutor.executeTargets(SingleCheckExecutor.java:38)
at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
at org.apache.tools.ant.taskdefs.Ant.execute(Ant.java:442)
at org.apache.tools.ant.taskdefs.CallTarget.execute(CallTarget.java:105)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
at org.apache.tools.ant.Task.perform(Task.java:348)
at org.apache.tools.ant.Target.execute(Target.java:390)
at org.apache.tools.ant.Target.performTasks(Target.java:411)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
at org.apache.tools.ant.Main.runBuild(Main.java:809)
at org.apache.tools.ant.Main.startAnt(Main.java:217)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)

The missing class (or method in this case) is most probably a sign that you already have asm in your class-path.

For Linux based distributions that provide modularized ANT tasks you may need to remove the package that provides asm task, so that Virgo build can use a different version. Example for this approach is Gentoo Linux that provides asm-ant that is older version than the required by Virgo.

If you are using Windows or Mac please check you classpath and remove asm. It is worth checking ANT's directories for older version of ASM tasks as well.